Iain Martin is a political commentator, and a former editor of The Scotsman and former deputy editor of The Sunday Telegraph. He is the author of Making It Happen: Fred Goodwin, RBS and the men who blew up the British economy, published by Simon & Schuster.. As well as this blog, he writes a column for The Sunday Telegraph. You can read more about Iain by visiting his website

Justine Greening and the third runway: George Osborne can't afford to sack her

Greening used to work for Osborne as a Treasury minister. Perhaps he is baffled by the prospect of someone having and sticking to her beliefs, which coincidentally (no third runway) were reflected in the Tory manifesto at the last election.

The accusation of a lack of maturity is a bit rich. The Chancellor's recent Budget wasn't exactly a grown-up enterprise. One might think he has enough on his plate, what with the ongoing economic emergency, without wasting time giving colleagues end-of-term reports as though he is head teacher.

But then this mud-slinging is the stuff on which quite a bit of Westminster life thrives. Despite all the public pleas for a focus on substance rather than personality, most gossip comes from the politicians themselves.

The briefing against Greening was all so childish it rather reminds me of one of those little rhymes in which the great Roald Dahl used to specialise: "She's angered George, she's in the soup, he's told his friends she's out the loop."

Actually, Greening is in a strong position and that Osborne's supporters cannot see that this shows they have not grasped that the "optics" have changed in recent months. The combined impact of the Budget and the omnishambles mean he would be well advised to concentrate on the day job.

Greening should refuse to budge. Not only is she right (the UK needs a proper new hub airport, as Boris Johnson argues, and not a third runway at the botched-job which is Heathrow). But she has leverage. If they remove her she will become a martyr in the eyes of some amongst the Tory rebel forces and to residents in south-west London. A cabinet minister who was right and was fired for it then becoming free to lead the anti-third runway campaign would be trouble the government can well do without.